Bending an object into a circle
Bend tool, which is a newer operator than Warp, and take Warp's shortcut Shift W, works a bit different from Warp. I think here you just need the old Warp tool. You can still find it in the menu.



Another way for bending objects is to use Simple Deform modifier. It will bend along the Local Z axis. You can also give it a try.